To a well-stirred solution of 1-[2-(4-cyanophenoxy)ethyl]-1-(2-hydroxy-ethyl)-3-methylurea (6.6 g, 0.0257 mol; see step (i) above) in dry THF (70 mL) was added n-BuLi (2.85 N, 1.766 g, 0.0276 mol) at −78° C., dropwise under a nitrogen atmosphere. After stirring at the same temperature for 45 min, p-toluenesulfonyl chloride (5.25 g, 0.0276 mol) in dry THF was added (drop by drop) and the reaction mixture was then stirred at −40° C. for 2 h. The reaction was quenched with 50 mL water and warmed to room temperature. The product was extracted with ethyl acetate, washed with brine solution and dried over sodium sulfate. Solvent evaporation under reduced pressure, followed by column chromatography over silica gel (using 15-25% methanol in chloroform) yielded 1.36 g of the title compound as a brown gummy liquid.
